This a letter of application to the MR to conduct immunoelectron microscopy on early C elegans embryos with a monoclonal antibody we developed that binds the C elegans centromere. This is a collaboration with John White. The purpose of the project is to determine where the antigen recognized by this antibody is concentrated relative to the Idnetochore. Our previous fight microscopic analysis of antibody stained embryos suggested mitosis specific expression of the antigen with the highest concentration on the poleward face of the holocentric chromosomes at metaphase. A limitation of fight microscopy is that we cannot distinguish whether the antigen is concentrated in the kinetochore or somewhere near it. DVM researchers experienced in immunoelectron microscopy may be able to overcome this limitation.